Process of drying explosives.



W. A. PHILLIPS.

PROCESS OF DRYING EXPLOSIVES.

APPLICATION FILED AUG-l3. 1913.

1,237,551. Patented Aug. 21,1917.

W. A. PHILLIPS.

PROCESS OF DRYING EXPLOSIVES.

APPLICATION FILED AUG- 13, 1913.

1,237,551 Patented Aug 21,1917.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

WILLIAM A. PHILLIPS,'OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T0 E. I. DUPONT DE NEMOUBS POWDER COMPANY, OF WILMINGTON, DELAWARE, A CORPORATIONOF NEW J EBSEY.

PROCESS OF DRYING EXPLOSIVES.

Specification of Letters Patent.

Patented Aug. 21, 1917.

Application filed August 18, 1913. Serial No. 784,486.

To all whom it may concern:

Be it known that I, WILLIAM A. PHILLIPS, of Philadelphia, in the countyof Philadelphia and in the State of Pennsylvania, have invented acertain new and useful Improvement in Processes of Drying Explosives,and do hereby declare that the following is a full, clear, and exactdescription thereof.

My invention relates to a process of drying explosives of many differentkinds and the product obtained thereby, but it has special reference todrying smokeless powder. It is to beunderstood, however, that myinvention is applicable to the drying of many diflerentproducts ofsimilar kind which are of such a nature that they may be dried inaccordance with my invention hereinafter set forth.

Hitherto, it has been customary to recover the solvents used inproducing smokeless powders, by methods which have been disadvantageousin many ways. Smokeless powders have been previously dried by thecirculation of hot air through the powder grains. The hot air thuscirculated through the .powder grains carried off the greater part ofthe solvent, this air being subsequently conducted to a condenser toremove the solvents from the current of air; the maximum amount ofsolvent that could be recovered in this manner was about sixty per cent;and it was necessary to treat the powder for a further period of fromone to four months in order to reduce the solvent still contained in thepowder to a sufficient extent to give proper ballistic results. But evenafter the drying of the powder for this extended period, a comparativelylarge percentage of solvent was still left in the powder, which solventwas not entirely uniformly distributed in the grains thereof, and

the grains furthermore showed signs of 7 strain and distortion. Again,the solvent retained in the grains is liable to become partiallyoxidized, to form hydrogen peroxid, ozone, acids, and otherobjectionable substances which may decompose the powder. And the vaporsof solvents evolved from the powder during storage in airtightcontainers are capable of forming an explosive mixture with the air,resulting at life of the powder by quickening the spontaneousdecomposition of the nitric esters, thus leading to the possibility ofgrave accidents. .A further disadvantage of said heating is the factthat a portion of the stabilizersis caused to escape by volatilization.A further frequent cause of decomposition is the presence of bacteria inthe powder.

The object of my invention is to provide a process and product wherebythe above disadvantages are avoided. By means of my invention,furthermore, a more complete recovery of the solvents is obtained, andthe powders thus produced show remarkable results in ballisticqualities, keeping qualities, resistance to the injurious influence ofmoisture, heat, etc.

My invention comprises in general the drying of powder by the use of aliquid, such for example, as oil. instead of by the application of air.The oil used for this purpose should preferably be stable and notsubject to chemical change. It must be free from acid, have a high flashpoint, and possess a low viscosity and a low solidifying point. An oilof this character will peneextract the solvents and absorb the sametherefrom by osmosis. The even drying avoids the strain and distortionswhich were produced in the grains dried by former processes.

My invention is capable of being carried out in many different ways,but, for the purpose of illustration, I have shown certain apparatuswhich may be used for the purpose of carrying out my invention, in theaccompanying drawings, in which,

Figure l is a diagrammatic representation of one form of apparatus thatmay be used for carrying out my invention,

Fig. 2 is a dlagrammatic representation of another form of apparatuswhich may be used for carrying out my invention.

Figs. '3 and t are diagrammatic representations of details of anIPPZLIQUISOI the type shown in Fig. 2,

Fig. 5 is a diagrammatic representation of another arrangement ofapparatus which may be used for carrying out my lnvention, an

' Figs. 6 and 7 are diagrammatic representations of details of a type ofapparatus such as that shown in Fig. 5.

. Reference being had particularly to Fig. 1, the powder from thecutters is conducted through a funnel 1, the lower end of which issealed Within a body of oil 2 contained within a tank 3. At its lowerend the tank 3 has baffles 4 to guide the grains of powder 'to a screwconveyer 5 located in the bottom of the tank 3 and having a shaft 6 andoperating handle 7 which extends laterally out through a horizontalextension 8 attached to the lower end of the tank 3. When the powdergrains have thus been received by the tank 3 they are thereafterconveyed by the conveyer 5 to a vertical drying chamber 9 which isattached to the end of the horizontal extension 8. The lower end of thevertical drying chamber is closed by a cover 10. When the powder hasbeen treated in the drying chamber 9 the conveyer 5 is moved to the leftof the apparatus, as shown in Fig. 1, and a valve 11, located inthehorizontal section 8, is moved upwardly so as to separate the tank 3from the drying chamber 9. Any vapors of solvents, such, for example, asether, alcohol, acetone, etc., that are produced in the tank 3 areconducted upwardly through a pipe 12 to a condenser 13, from which theliquid solvents are conducted to a receptacle 14. The con denser 13, asin the case of all the other condensers to be referred to in thisapplication, may be cooled by a current of water, or in any otherdesired manner. The solvent vapors which are formed in the dryingchamber 9 are conveyed through a pipe 15 to a condenser 16, from whichthe condensed solvents are collected by means of a receptacle 17. Meansare provided for circulating a body of oil in the tank 3 and in thedrying chamber 9 and also forwithdrawing the oil from the drying chamber9. This is accomplished by means of an oil chamber 18 having aheatingcoil'19 therein preferably provided with a supply of steam. The heatingchamber 18 is connected to the top of the tank 3 by a valved pipe 20 andto the bottom of the tank 3 by a valved pipe 21, the latter beingprovided with a circulating pump 22. The oil chamber 18 is alsoconnected to the top of the drying chamber 9 by a valved pipe 23 and tothe bottom thereof by pipes 24 and 25. The pipes 24 and 25 are connectedto each other by two parallel pipe connections 26 and 27, each of whichhas a pair of valves 28, 29, 30 and 31 A pump 32 is provided in anotherpipe 33 which is bridged between the pipe connections 26 and27 at pointslocated between the pairs of valves, as indicated in Fig. 1.

Any vapors that areformed in the oil chamber 18 are conveyed upwardlythrough a pipe 34 to a condenser 35, from which the condensed solventsare collected by means of a receptacle 36. a

I have shown somewhat similar arrangements in the other figures. In thearrangement shown in Figs. 2, 3 and 4, the powder grains are deliveredinto a series of movable containers or drying chambers 37-, each ofwhich has a column 38, which may be 'connected to a pipe 39 leading to acondenser 40, having a discharge receptacle 41 for the condensedsolvents. If desired, the movable containers 37 may have doors 37 nearthe bottom thereof to facilitate the removal of the powder. The samecondenser 40 is arranged in this instance to receive vapors by means ofa pipe 42 from an oil chamber 43, provided with heating coils 44 in thesame manner as in the arrangement shown in Fig. 1. Pipes similar tothose shown in Fig. 1 as being connected to the oil chamber 18 areprovided in this instance. Circulating pipes 45 and 46 are provided tocirculate heated oil through the containers 37 and a third pipe 47 isprovided to draw the oil from the containers. Pipes 46 and 47 aresupplied with pumps 48 and 49 to bring about the movement of the oil inthe pipes 46 and 47. As shown in Fig. 4, each of the containers may becarried upon a skid 50 having wheels 51 so as to permit the same to bereadily moved from one point to another in the plant.

The arrangement shown in Figs. 5, 6 and 7 is constructed in a mannersomewhat similar to that shown in Figs. 2, 3 and 4. In this instance,however, the powder grains are carried in a wire cage or bag 52 made inany desired manner, said wire cage or bag 52 being received in movablecontainers or drying chambers 53 situated upon movable skids 54 havingwheels 55. The top of each of the movable containers 53- has a waterseal 56 in which is received the larger end of a solvent header 57. Thesmaller ends of the solvent headers 57 communicate with a common pipe 58leading to a condenser 59 having a discharge receptacle 60. In thisinstance, an oil tank 61 is provided, having pipes 62 and 63 connectedby means of branches 64 and 65 with the containers, 53

in order to circulate oil through the same. i

In this modification a pair of valves 66 and 67 are provided in the pipe62 and a similar pair of valves 68 and 69 are provided in the pipe 63. Apump 7 O is located in a pipe 71 bridging the two pipes 62 and 63between the two" pairs of valves just referred to. At their ends thepipes 62 and 63 may be connected 4 together and have a valve 72 atthepoint where the pipes are connected. In this arrangement the oil is hotheated in the oil chamber 61, but there may be provided in-v steadheating coils 73 in each of the chambers 53, said heating coils beingconnected by means of valved pipes 74 and 75 to steam pipes 7 6 and 77in order to provide a supply of steam for the heating coils.

In the operation of 'my process, I shall refer to the same first inconnection with the use of the apparatus shown in Fig. 1. The powderfrom the cutters is conveyed into the tank 3 filled with a suitable bodyof oil to efiect the drying of the powder. The powder is conveyed intothe tank 3 through the funnel 1, the lower end of which is sealed in thebody of oil, so that no vapors arising from the powder and the oil canescape from the tank 3. As soon as the powder has become immersed in theoil, the transfer of the solvent from the powder to the oil begins evenat ordinary temperatures, and the volume of the liquid increases as thevolume of the powder decreases. The transfer of solvent from the powderto the oil may be hastened by circulating warm or hot oil from the oilchamber 18, the oil in which may be heated by means of the steam coils19 therein'. In order to effect the circulation of the oil at thisperiod in the process, the pump 22 may be operated so as to circulatethe oil from the oil chamber 18 through the valved pipes 20 and 21. Anysolvent vapors which arise from the tank 3 during such treatment arecondensed in the condenser 13 and conveyed to receptacle 14. The powderwhich has been subjected to this preliminary treatment may be thenremoved by means of the conveyer5 to the drying chamber 9. If desired,the process may, in fact, be carried out continuously by continuallyfeeding in the powder through the funnel 1 and intermittently removingthe same through the door 10 from the drying chamber 9, in the manner tobe hereinafter described. If desired, after the powder grains have beenconveyed to the drying chamber 9, the conveyer 5 may be withdrawn totheleft of valve 11 shown in Fig.1 and said valve 11 may be closed so asto separate the tank 3 from the drying chamber 9. Oil may then becirculated, if desired, in the drying chamber 9 by means of the pump 32,the valves 28, 29, 30.and 31 being in proper position, until the solventin the powder has been removed. Any vapors which are evolved by thetreatment in tllu drying chamber 9 are condensed in the condenser '16and recovered in the receptacle 17, and any vapors which are evolved atany stage in the process from the oil chamber 18 are condensed inthe-condenser and collected in the receptacle 36. If now it is desiredto remove the powder from the drying chamber 9, the oil is withdrawnfrom the same by closing the valve in the pipe 23 and operating the pumpwith the valves 28, 29, 30 and 31 in proper position for this purpose.The oil having been drained from the drying chamber 9 in this manner,the door 10 is detached and the body of powder removed from the dryingchamber. If. desired, the powder removed from the drying chamber 9 canbe subjected to a washing operation with gasolene, or other solvent ofthe oil remaining upon the powder, so as to remove said oil therefrom.And to remove the gasolene or other similar solvent the powder may besubjected to aeration.

The operation of the form of apparatus shown in Figs. 2, 3 and 4 is, ingeneral, the same as in the case of the operation of my invention withthe apparatus shown in Fig. 1. It differs, however, in the followingrespects: The movable containers 37, having been charged with a quantityof powder while on the movable skids, said containers are moved into aposition in which the several pipes of the apparatus may be connected,and the solvent pipes 38 are then connected to the pipe 39, and pipes45, 46 and 47 are also connected to the containers 37. Heated oil maynow be circulated from the oil chamber 43 to the several containers 37until the powder therein has been sufficiently dried. Meanwhile, anyvapors evolved from the containers 37 and the oil chamber 43 arecondensed in the condenser 40 and recovered in receptacle 41. After thepowder has been dried in this manner, the oil circulating pipes areclosed by turning the valves located therein and the oil in thecontainers 37 is removed by means of pipe 47 through the operation ofthe pump 49. The containers 37 may now be disconnected and conveyedtoany suitable place where the powder located therein may be subjectedto a washing operation with gasolene, or other suitable solvent of theoil, so as to remove the remainder of the oil present on the powder. Thesolvent remaining on the powder may be removed by aeration, if desired.'In order to economize space, the several containers may be operatedwhen nearly filled with powder. It is to be understood, however, thatthe several containers 37 may be operated. in such a manner that thetreatment of the bodies of powder in the several containers may befinished in sequence so as to economize time, labor, etc. It is also tobe understood that, if desired, the circulation of the oil may beeffected through the several containers in sequence on the countercurrent principle, so that the body of powder which has been subjectedto the longest period of treatment is being subjected to oil comingdirect from the oil chamber, while the other containers receive the oilfrom the first mentioned conexcept in the following respects: In thisinstance, the cages 52, having been charged with suitable quantities ofpowder, are placed the receptacles 53 and are then moved upon themovable skids 54 to their proper positions to permit the various pipesof the drying system to be connected thereto. in position so that theyare connected to the common pipe 58, and the remainingpipes of thesystem are connected to the containers 53. Oil is now circulated fromthe oil receptacle 61 through the containers 53 and, if it is desired tocirculate a heated current of oil, currents of steam are led through theheating coils 73 in the bottom of the containers. Any vapors produced inthe system in this instance are evolved from the containers 53 and arethereupon condensed in the condenser 59 and recovered from thereceptacle 60. When the drying operation has been completed, the oilpresent in the containers is removed by'means of the pump 70 andconveyed into the oil chamber 61. In this instance, the severalcontainers may be operated in serial order in the manner described inconnection with the apparatus shown in Figs. 2 to 4:.

In the treatment by means of oil in the process as carried out inconnection with the apparatus shown in the several modified formsalready described, the oil is caused to mix homogeneously, so that allportions of the oil are brought into intimate and uniform contact withthe powder under treatment. As a result, there is also an agitationwithin the bodies of powder which carries off any air bubbles.Furthermore, the circulation of the liquid through the bodies of powderdistributes the heat uniformly throughout the same, so that thereby thesolvent is uniformly transferred to the oil in an efficient manner.Powder which is treated in this manner may be dried in a few days,whereas the previous method in use, involving the application of heatedair, required a period of several months to complete the dryingoperation. .The use of oil causes the powder to be more quickly dried,owing to the greater conductivity of oil for heat and, furthermore,permits the transfer of a' large number of thermal units to the powderin a short time without unduly rais-' ing the temperature thereof.Furthermore, thereis a more complete contact between the oil and thepowder, as the oil penetrates and permeates the grains thoroughly. Theoperation is such as to cause an eflicient re-. moval of the solventfrom the powder by osmosis. The treatment of powder in accordancewith myinvention is for such a short period of time that practically nodeterioration of the powder takes place, and

there is consequently avoided the disadvantageous result of previousprocesses in which The solvent headers 57 are then placed the rate ofspontaneous decomposition increases rapidly during storage, the rapidityof decomposition being. greater the longer the powder has been subjectedto elevated temperatures. It will thus be seen that powders dried inaccordance with my invention have a longer period of life and may becarried in storage and handled with much greater safety than the powdersdried by former processes. Furthermore, on account of the absence ofsolvent vapors evolved during storage, there is not the tendency to formexplosive mixtures with air, which makes powders dried by previousprocesses unsafe when stored for a considerable length of time. Thecirculation of the oil, in addition to expelling air bubbles, also hasthe effect of expelling the water which is found in the powder mass andwhich has been left therein from the solvents used, which sol-, ventscontain about 7% of water, and also expelling the microscopic drops ofwater which have condensed on" the grains during their shaping andcutting. The presence of such moisture would contribute considerably tothe deterioration of the powder, a fact which is proven by the shortlife of pow-, ders in moist climates. Besides bein anhydrous, thepowders dried in accordance with my invention are non-hygroscopic, owingto the fact that a slight amount of the oil remains in the grains afterthe treatpowders to neutralize the traces of acid fumes evolved duringspontaneous decomposition. If desired in the treatment in accordancewith my process, in order to avoid any loss of the diphenylamin or otherstabilizers by solutionin the oil, a quantity of the stabilizer may beadded to the oil before treatment of the powder. The temperature of theoil in the treatment of the powder may be as high as 100 0., or evenhigher, and the various arts of the apparatus may be constructed, ifdesired, in such a manner as to make use of such temperatures. It willalso be seen that the treatment in accordance with my invention destroysall bacteria contained in the powder by sterilization.

In addition to the advantages pointed out above, there are still furtheradvantages in eration may be more readily controlled than in the case ofprevious processes. Again, the circulating oil does not depend, as inthe case of heated air, for the removal of solvent through the action ofvapor tension, but is accomplished by osmosis. The amount of heatexpended inthe process is very small and the plant necessary forcarrying out the .process is not large.

While I have described my invention in detail, I wish it to beunderstood that many changes may be made therein without departing fromthe spirit of my invention.

I claim:

1. The process which comprises removing a liquid from a solid materialsoluble therein, by bringing said material into contact with anon-solvent oil miscible with said liquid.

2. The process which comprises removing a liquid from a smokeless powdersoluble therein, by bringing said material intocontact with anon-solvent oil miscible with said liquid. 1

3. The process which comprises removing a liquid fronl a smokelesspowder soluble therein, by bringing said material into contact with anon-soluble oil miscible with said liquid, by circulating a body of theheated oil through a body of the powder.

4. The process which comprises removing a liquid from a smokeless powdersoluble therein, by bringing said material into contact with anon-solvent oil miscible with said liquid, by circulating a body. of theheated oil through a body' of the-fiiowder,

and drawing oif the oil.

5. The process which comprises removing a liquid from a smokeless powdersoluble k therein,'by bringing said material into contact with anon-solvent oil miscible with said liquid, by circulating a bgdyof theheated oil through a body of the powder, drawing therein, by bringingsaid material into con tact with a non-solvent oil miscible with saidliquid, by circulating a body of the heated oil through a body of thepowder while recovering any escaping solvent vapors, and drawing ofl theoil.

7. The process which comprises removing a liquid from a smokeless powdersoluble therein, by bringing said material into consaid liquid, bycirculating a body of the heated oil through a .body of the powder whilerecovering any escaping solvent vapors, drawing off the oil, andremoving the remainder of the oil by washing with a solvent thereof.

8. The process which comprises removing a nitrocellulose solvent andwater from smokeless powder byapplying oil thereto.

9-. The process which comprises drying smokeless powder by subjectingthe same to a body of an oil containing a stabilizing agent.

10. The process which comprises drying smokeless powder by subjectingthe same to a body of a heated oil containing diphenylamin.

11. The process which comprises removing a nitrocellulose solvent andair-bubbles from smokeless powder by 'applylng o1l thereto.

- 12. The continuous'process which comprises feeding a quantity ofsmokeless powder containing a solvent .into a body of heated oil,circulating the body of oil in the body of powder, recovering solventvapors escaping from the body of oil, segregating the treated powder inthe body of oil, cutting ofi the segregated body of powder from the mainbody of oil, withdrawing ingthe same with a solvent of the oil, removingthe solvent by aeration, and feeding into the main body of oil anotherbody of powder containing a solvent to be treated.

In testimony that I claim the foregoing I 'have hereunto set my hand. 4

WILLIAM A. PHILLIPS. Witnesses:

S. W. FOULKROD, E. N. KEMP.

.tact with a non-solvent oil miscible with .the oil from the segregatedpowder, wash-

